Researchers compared omega-3 fatty acid levels in the blood of vegans, vegetarians, pescatarians, and meat-eaters. They found that vegans and vegetarians who don’t eat fish have significantly lower levels of important omega-3s called EPA and DHA in their red blood cells compared to those who eat fish or meat. The study suggests that vegans and vegetarians may benefit from taking algae-based supplements to reach recommended omega-3 levels, since these fatty acids are naturally found mainly in fish and seafood.

The Quick Take

  • What they studied: Whether different eating patterns (vegan, vegetarian, pescatarian, and meat-eating) affect omega-3 fatty acid levels in the blood
  • Who participated: 241 adults from the Adventist Health Study, divided equally into four diet groups: vegans (no animal products), lacto-ovo vegetarians (dairy and eggs but no meat), pescatarians (fish but no meat), and non-vegetarians (eat all foods)
  • Key finding: Vegans had omega-3 levels of 3.7 and vegetarians had 3.9, while pescatarians had 5.7 and meat-eaters had 5.0. These numbers show vegans and vegetarians had about 25-35% lower omega-3 levels than the other groups.
  • What it means for you: If you’re vegan or vegetarian, your omega-3 levels may be lower than recommended. Taking an algae-based omega-3 supplement could help bring your levels up to a healthier range, though you should talk to your doctor first.

The Research Details

Researchers selected 300 people from a large health study, with 75 people in each diet group (vegan, vegetarian, pescatarian, and meat-eater). They asked participants detailed questions about what they ate and then tested their blood to measure omega-3 fatty acid levels. The blood test specifically looked at red blood cells, which store these fatty acids and can show long-term omega-3 status.

The researchers used a method called gas chromatography, which is like a scientific fingerprint reader for fatty acids. It can identify and measure exactly how much of each type of fatty acid is in the blood. They also removed people who were taking fish oil supplements to get a true picture of omega-3 levels from diet alone.

This type of study is called cross-sectional, meaning researchers took a snapshot of people at one point in time rather than following them over years. This helps identify patterns but can’t prove that diet directly causes the differences in blood levels.

Understanding omega-3 levels across different diets is important because omega-3s play crucial roles in heart health, brain function, and reducing inflammation in the body. Since vegans and vegetarians can’t get EPA and DHA from fish, knowing whether they’re getting enough from other sources helps doctors and nutritionists give better advice. This research provides real blood data rather than just guessing based on food intake.

The study’s strengths include using a validated food questionnaire and precise laboratory testing of blood samples. The sample size of 241 people is reasonable for this type of research. However, the study only looked at one point in time, so we can’t know if these patterns stay the same over years. The participants were mostly from Adventist communities, which may not represent all vegans and vegetarians. Also, the study couldn’t prove that diet causes the differences—only that they exist together.

What the Results Show

Vegans had the lowest omega-3 levels (3.7), followed closely by vegetarians (3.9). Pescatarians had higher levels (5.7), and meat-eaters had 5.0. The difference between vegans/vegetarians and pescatarians was quite large—pescatarians had about 50% more omega-3s in their blood.

When researchers looked at actual food intake, vegans ate only 10 mg of EPA and DHA per day, vegetarians ate 18 mg, pescatarians ate 158 mg, and meat-eaters ate 117 mg. This shows a very strong connection: the more EPA and DHA someone ate, the higher their blood levels were (this relationship was very statistically significant, with a correlation of 0.67).

Interestingly, the ratio of two other fatty acids (linoleic acid to alpha-linoleic acid) didn’t affect omega-3 levels. This means that eating more of certain plant-based fatty acids won’t automatically increase EPA and DHA levels in the blood.

The study found that eating more linoleic acid (a common plant-based fatty acid) didn’t increase arachidonic acid levels in red blood cells. This suggests the body doesn’t simply convert one type of fatty acid into another at high rates. The findings support the idea that EPA and DHA are somewhat unique—the body can’t easily make them from other sources.

Previous research suggested vegans might have lower omega-3 levels, but this study provides actual blood measurements from a large group. The findings align with what nutrition experts have suspected: plant-based diets naturally contain very little EPA and DHA since these fatty acids come mainly from fish and algae. The strong correlation between dietary intake and blood levels confirms that diet is the main factor determining omega-3 status.

The study only included people from Adventist communities, who may be healthier or have different eating habits than the general population. The researchers only measured omega-3 levels once, so they couldn’t track changes over time. Some people may have underreported or overreported their food intake on the questionnaire. The study couldn’t prove that low omega-3 levels cause health problems—only that vegans and vegetarians have lower levels. Finally, the study excluded people taking fish oil supplements, so results don’t apply to supplemented individuals.

The Bottom Line

If you’re vegan or vegetarian, consider taking an algae-based EPA and DHA supplement to reach recommended levels (most experts suggest 200-300 mg per day combined). This recommendation has moderate confidence based on this research showing low levels in vegans and vegetarians. Talk to your doctor or registered dietitian about the right dose for you. Pescatarians eating fish regularly appear to get adequate levels without supplements.

Vegans and lacto-ovo vegetarians should pay attention to this research and consider their omega-3 intake. Pescatarians eating fish 1-2 times per week likely have adequate levels. Meat-eaters also appear to get enough. Pregnant women, nursing mothers, and people with heart disease should especially discuss omega-3 status with their healthcare provider. People already taking fish oil supplements don’t need to worry about this finding.

If you start taking an algae-based omega-3 supplement, it typically takes 4-12 weeks for blood levels to increase noticeably. You might not feel any immediate difference, but your blood levels should improve within this timeframe. Long-term benefits for heart and brain health develop over months to years of consistent adequate intake.

Want to Apply This Research?

  • Track daily omega-3 supplement intake (yes/no) and note the dose in mg. Also track fish or seafood consumption if applicable. Set a goal of taking your supplement 5-6 days per week and monitor compliance.
  • If you’re vegan or vegetarian, add a daily algae-based omega-3 supplement to your routine. Take it with a meal containing fat for better absorption. Set a phone reminder at the same time each day (like with breakfast) to build the habit.
  • Check in monthly on supplement adherence. After 3 months, consider asking your doctor for a blood test to measure your omega-3 levels and confirm the supplement is working. Continue tracking intake long-term to maintain adequate omega-3 status.

This research shows that vegans and vegetarians have lower omega-3 levels in their blood, but it does not prove that these lower levels cause health problems or that supplements will prevent disease. Before starting any supplement, especially if you take medications, are pregnant, nursing, or have existing health conditions, consult with your doctor or registered dietitian. This information is for educational purposes and should not replace professional medical advice. Individual nutritional needs vary, and a healthcare provider can help determine if omega-3 supplementation is right for you.